Method of adhesive selection for cold forming product and process

Abstract

Aspects of this disclosure relate to a method for selecting an adhesive for bonding a cold-formed glass to a metal substrate and various cold-formed products. In one or more embodiments, the cold-formed products include a structural substrate comprising a curved surface and structural substrate coefficient of thermal expansion (CTE), a cold-formed and curved glass substrate attached to the curved surface with an adhesive, the glass substrate comprising a glass substrate CTE, the structural substrate and adhesive forming a structural substrate/adhesive interface and the glass substrate and the adhesive forming a glass substrate/adhesive interface, wherein the glass substrate CTE and the structural substrate CTE differ, wherein the product withstands overlap shear failure as determined by modified test method ASTM D1002-10 at −40° C., 24° C., and 85° C. and tensile failure as determined by ASTM D897 at −40° C., 24° C., and 85° C. at one or both of the structural substrate/adhesive interface and the glass substrate/adhesive interface.

1 . A method for selecting an adhesive for bonding a cold-formed glass to a metal substrate, the method comprising:
 calculating at least one of the ambient stress and ambient strain of the adhesive on the metal substrate;   calculating an ambient stress to strength ratio of the adhesive;   calculating at least one of the stress and strain of the adhesive on the metal substrate as a function of temperature;   calculating a stress to strength ratio of the adhesive as a function of temperature; and   selecting the adhesive if the ambient stress to strength ratio changes less than an order of magnitude as a function of time.   
     
     
         2 . The method of  claim 1 , wherein the calculating of at least one of the ambient stress and ambient strain of the adhesive on the metal substrate is based on at least one of a thickness of the cold-formed glass, a thickness of the metal substrate, and a thickness of the adhesive. 
     
     
         3 . The method of  claim 1 , wherein the calculating of at least one of the ambient stress and ambient strain of the adhesive on the metal substrate is based on a physical property of at least one of the cold-formed glass, the metal substrate, and the adhesive, wherein the physical property is at least one of: the elasticity, hyper-elasticity or viscoelasticity of the cold-formed glass, the elasticity, hyper-elasticity or viscoelasticity of the metal substrate, the elasticity, hyper-elasticity or viscoelasticity of the adhesive, and the glass transition temperature (T g ) of the adhesive. 
     
     
         4 . (canceled) 
     
     
         5 . The method of  claim 3 , wherein the Tg is about or below about room temperature such that the difference in the storage modulus (E′) of the material at its lowest operating temperature and highest operating temperature is at about or less than about three orders of magnitude or at about or less than about two orders of magnitude. 
     
     
         6 . The method of  claim 3 , wherein the T g  of an adhesive is at or below room temperature. 
     
     
         7 . The method of  claim 1 , wherein the calculating of at least one of the ambient stress and ambient strain of the adhesive on the metal substrate is based on a bending radius of the cold-formed glass. 
     
     
         8 . The method of  claim 1 , wherein the calculating at least one of the stress and strain of the adhesive on the metal substrate as a function of temperature is based on at least one of a thickness of the cold-formed glass, a thickness of the metal substrate, and a thickness of the adhesive. 
     
     
         9 . The method of  claim 1 , wherein the calculating at least one of the stress and strain of the adhesive on the metal substrate as a function of temperature is based on a physical property of at least one of the cold-formed glass, the metal substrate, and the adhesive, wherein the physical property is at least one of: the elasticity, hyper-elasticity or viscoelasticity of the cold-formed glass, the elasticity, hyper-elasticity or viscoelasticity of the metal substrate, the elasticity, hyper-elasticity or viscoelasticity of the adhesive, and the glass transition temperature of the adhesive. 
     
     
         10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein the calculating at least one of the stress and strain of the adhesive on the metal substrate as a function of temperature is based on a bending radius of the cold-formed glass. 
     
     
         12 . (canceled) 
     
     
         13 . The method of  claim 1 , wherein the ambient stress to strength ratio changes from about 3:10 to about 3:100 as a function of a 15 year time period. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . The adhesive of  claim 1 , wherein the adhesive is a polyurethane, a polysiloxane or an epoxy. 
     
     
         17 . (canceled) 
     
     
         18 . The adhesive of  claim 1 , wherein the adhesive is a polysiloxane or a silane-modified polymer. 
     
     
         19 . An automotive part comprising:
 a metal substrate having a first major surface;   a cold-formed glass having a first major surface; and   an adhesive having a first major surface and a second major surface, the adhesive selected using the method of  claim 1 ;   wherein:   the adhesive is located between the metal substrate first major surface and the cold-formed glass first major surface; and   the adhesive bonds the metal substrate first major surface to the cold-formed glass first major surface.   
     
     
         20 . The automotive part of  claim 19 , wherein the adhesive is a polyurethane. 
     
     
         21 . A cold-formed product comprising:
 a structural substrate comprising a curved surface and structural substrate coefficient of thermal expansion (CTE);   a cold-formed and curved glass substrate attached to the curved surface with an adhesive, the glass substrate comprising a glass substrate CTE, the structural substrate and adhesive forming a structural substrate/adhesive interface and the glass substrate and the adhesive forming a glass substrate/adhesive interface,   wherein the glass substrate CTE and the structural substrate CTE differ,   wherein the product withstands overlap shear failure as determined by modified test method ASTM D1002-10 at −40° C., 24° C., and 85° C. and tensile failure as determined by ASTM D897 at −40° C., 24° C., and 85° C. at one or both of the structural substrate/adhesive interface and the glass substrate/adhesive interface.   
     
     
         22 . The product of  claim 21 , wherein the glass substrate comprises an ink layer forming an inked surface that is in contact with the adhesive at the glass substrate/adhesive interface. 
     
     
         23 . The product of  claim 21 , wherein the cold-formed and curved glass substrate comprises a radius of curvature and the structural substrate comprises a radius of curvature, wherein the radius of curvature of the glass substrate and the structural support are within 10% or less of one another. 
     
     
         24 . The product of  claim 21 , wherein the glass substrate radius of curvature is greater than or equal to about 400 mm, and wherein the product comprises at least one of:
 the adhesive comprising a modulus in a range from about 0.5 MPa to about 5 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 120 ppm/° C.; the adhesive comprising a modulus in a range from about 5 MPa to about 15 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 120 ppm/° C.;   the adhesive comprising a modulus in a range from about 15 MPa to about 100 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 120 ppm/° C. at 15 MPa and decreasing linearly to a range from about 0 ppm/° C. to substrate CTE of about 60 ppm/° C. at 100 MPa;   the adhesive comprising a modulus in a range from about 100 MPa to about 500 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 60 ppm/° C. at 100 MPa and decreasing linearly to a range from about 0 ppm/° C. to substrate CTE of about 3 0 ppm/° C. at 500 MPa;   the adhesive comprising a modulus in a range from about 500 MPa to about 1000 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 30 ppm/° C. at 500 MPa and decreasing linearly to a range from about 0 ppm/° C. to substrate CTE of about 15 ppm/° C. at 1000 MPa; and   the adhesive comprising a modulus in a range from about 1000 MPa to about 10000 MPa and wherein the structural substrate CTE is from about 0 ppm/° C. to about 15 ppm/° C.   
     
     
         25 . The product of  claim 21 , wherein the glass substrate radius of curvature is greater than or equal to about 150 mm and less than 400 mm, and wherein the product comprises at least one of:
 the adhesive comprising a modulus in a range from about 2 MPa to about 5 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 120 ppm/° C.;   the adhesive comprising a modulus in a range from about 5 MPa to about 15 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 120 ppm/° C.;   the adhesive comprising a modulus in a range from about 15 MPa to about 100 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 120 ppm/° C. at 15 MPa and decreasing linearly to a range from about 0 ppm/° C. to structural substrate CTE of about 60 ppm/° C. at 100 MPa;   the adhesive comprising a modulus in a range from about 100 MPa to about 500 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 60 ppm/° C. at 100 MPa and decreasing linearly to a range from about 0 ppm/° C. to structural substrate CTE of about 3 0 ppm/° C. at 500 MPa;   the adhesive comprising a modulus in a range from about 500 MPa to about 1000 MPa and wherein the structural substrate CTE is in a range from about 0 ppm/° C. to about 30 ppm/° C. at 500 MPa and decreasing linearly to a range from about 0 ppm/° C. to a structural substrate CTE of about 15 ppm/° C. at 1000 MPa; and   the adhesive comprising a modulus in a range from about 1000 MPa to about 10000 MPa based on a structural CTE from about 0 ppm/° C. to about 15 ppm/° C.   
     
     
         26 . The product of  claim 21 , wherein the structural substrate is one of a metal, a hybrid of metal, plastic, or fiber reinforced composite.